PLECTRANTHUS — Coleus’ Cousin

rick’s weed-read

Textured, colorful foliage and a nice habit make plectranthus one of the best new plants for mixed containers.

By Richard Schoellhorn P. ecklonii ‘Erma’

ith all the well-deserved attention that coleus Why Weeds? hybrids are receiving for their landscape and interi- In our industry, things are changing very quickly as floriculture adjusts to becoming a orscape performance, it commodity to the American consumer. It’s really only beginning — we have a long way to seemsW like a good time to take a look at some of go. In my view, the future of the greenhouse business looks a lot like the history of the the closer relatives of coleus that have the same American farmer, but nurseries have an advantage. We watched what happened to the small strong characteristics and solid performance. farmer; we know what is needed to make the transition; and we have excellent examples of As with coleus, plectranthus are fast-crop successful small farmers around us today. So as we face the same forces shaping our annuals; salable almost as soon as they are rooted industry, we can avoid a lot of the pitfalls that the small farmer faced. and tolerant of a variety of production condi- Rick Shoellhorn This stuff has all been written before. Increasing market pressures will force the formation of tions. As the primary interest is foliage, plants major nurseries; these mega-nurseries’ sole purpose will be to supply the demand for flowers at can remain in good condition on retail shelves for the retail level. As these large corporations grow, the small local nurseries are going to need to change as well. Small longer periods of time. Use plectranthus as you nurseries are going to need to develop specialized products and services that separate them from the mega-nursery. If would coleus, although since leaf colors aren’t as they fail to do this, they will disappear because, to the consumer, they will become invisible. Quality won’t be enough to vivid, plectranthus will sell best as accent crops, save the small nursery; it wasn’t enough to save the small farmer. The average consumer can’t tell the difference between foliage filler and mixed container materials. With an average and a superior product…unless you are there to tell them the difference. the flowering types of plectranthus, schedule to Don’t get the wrong impression; the formation of mega-nurseries isn’t evil; it is a fact of life make the most of the season and use for color for our industry, as is the development of the big box garden center. This is our future, it is the and as value-added hanging baskets. In spring cost of becoming something Americans feel is a necessary part of life. Imagine how the corner 2000, plectranthus was one of the plants of focus market felt when the first supermarket came along — probably a bit like the smaller nursery at the University of Florida trials and showcased feels today. The message is change; the medium is plant materials and services, and the whole at the annual May field day. thing is progress whether it seems like it right now or not. Plectranthus are like coleus and salvia, So why a column on a bunch of weird crops that have small market share? Because they offer P. fruticosus members of the mint family, with rapid something different; they give smaller operations an edge in the market, and honestly, because I love growth, aromatic foliage and a variety of

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shapes and sizes. Like coleus, where they are used as bedding is around October first. Timing SUGGESTED VARIETIES these plants will do well in the and flowering hedge material. schedules for the flowering plec- The best-known flowering form irrigated landscape, container While the flowering mechanism is tranthus are still a bit sketchy, but in our industry is ‘Mona Lavender’ gardens and indoor situations as still being worked out, they appear the industry should be able to get a from Ball Floraplant. This plant has long as light levels are high. In to flower best in late summer as winter/spring flowering crop and a great form for containers and fact, many of the best known nights cool and day length begins perhaps another in the late sum- hanging baskets. Mona forms a low plectranthus are for the indoor to shorten, which in north Florida, mer and fall. mound, requires a pinch in ➧ market. Most plectranthus are used for foliage interest and have insignificant flowers, with a few notable exceptions. With all the interest in new crops, groups of plectranthus are coming onto the market with pro- fuse and very attractive flowers and green, aromatic foliage. The flowering plectranthus group is predominantly from South Africa,

these plants. While all these giant operations are form- ing and learn- P. madagascariensis ing how to control big markets, there is a lot of money to be made by personalizing what you do. I think a conservative adoption of new crops is a good ﬁrst step in differentiating your nursery from your competition. It’s only a step though, because you’ll need to know how to use these plants, how to present them differently and how to provide services that augment your original crops. So this column is here to promote new crops. Not all of them will work for you, but some will, and by carrying them as part of your crop mix, perhaps you’ll attract a few new customers. New crops are always a complicating factor in nursery production. They cause problems; they sometimes fail; but every production nursery should develop a crop experiment program, because it keeps you thinking about change. Also, getting new crops out in the press raises the awareness of our industry’s plant breeders. This column will also promote the new markets that are always coming along and offer ideas to nurserymen looking for niche markets. So I hope you enjoy this concept column, and I’ll try to make something productive out of my 15 minutes of fame by giving you some ideas — some reminders — that there’s always something new coming down the pipes. If there’s a group of plants you’d like to hear more about, please contact me, and I’ll work on getting some of the basics out to you. GPN

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production to get the best shape plectranthus ecklonii, which reaches a to the fall landscape. They can toler- and flowers profusely from all height of 4-5 feet and flowers with a ate full sun, but foliage is best when nodes. While Mona has deservedly rich, blue-purple, 6-inch spike from some protection from strong sun is the best recognition of the flowering all terminals, and plectranthus eck- provided. As a side note, the “fra- types, there are many other notable lonii ‘Erma’, a pink flowered form. grance” of the foliage is probably a varieties. Some other forms current- Both plants are annuals, even in bit of an exaggeration; stench might ly in southern region trade include north Florida, but add strong color be more accurate. We nicknamed P. amboinicus these plants “Smelly Dog Plant”, as the foliage odor was pretty close that of a wet dog. However, this name actually stimulated interest in the plant; it was one of the most popular plants in the Milton trials. Foliage types of plectranthus vary a lot in growth habit and form but are predominantly colored in shades of green, gray-green to silver and white, the most common of these forms being plectranthus amboinicus — Cuban Oregano. While this is not a “true” oregano, the foliage is highly aromatic, and the leaves are generally white edged with green centers. Growth habit for Cuban Oregano is loosely upright or mounding, reaching a height of 24 inches in the landscape. This plant will sport back to a solid green form, so propagators need to keep an ➧

Production guidelines for plectranthus:

Fertilization. 150 ppm liquid feed or a low level of slow release.

Watering. Normal production irrigation, drought stress works to slow growth.

Media. All commercial peat lite medias work ﬁne, pH 6-7, high EC will reduce growth and leaf size.

Production Temperatures. Ranges of 50-85º F are best, below 50º F growth slows dramatically.

Light level. Plants are pretty ﬂexible in most cases, 2,000-5,000 foot candles is ideal.

Propagation. All are propagated by cuttings, which root in 5-10 days. Seed for rarer species is available from sup- pliers in South Africa.

Crop timing. For a 4-inch pot, 4-6 weeks; hanging baskets (3-5 cuttings per) take 8-10 weeks.

Flowering. With ﬂowering varieties, ﬂowering is related to SD photoperiod and reinforced by cool night conditions.

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eye on stock plants as the green ‘albo-marginatus’, Forster’s plec- hold onto their leaves, so flower- Plectranthus madagascariensis, form is much more vigorous than tranthus. This is also a green-white ing is a good thing in this case, Variegated Mint Leaf, is another the variegated form. Allan variegated form but with larger unlike coleus. old time plant making a come back Armitage, and the University of leaves, a more upright growth habit Plectranthus australis (verticilla- because it takes bright light, grows Georgia, released ‘Athens Gem’, a and a more refined look to the tus), Swedish Ivy, is an old stan- fast and easy, and has an arching, tri-color variegation that is quite plant. Leaves are corrugated olive dard houseplant and hanging creeping growth habit that works nice. Try using Cuban Oregano in green with a clean white border. basket plant that has literally in both baskets and mixed contain- mixed containers for sturdy summer Plants rarely flower and have a bet- been hanging around for years — ers. Green leaves reach up to 1 inch foliage color, as an annual in the ter growth habit in the landscape and for good reasons; it holds up in diameter with clear white mar- landscape and pared with herbs than Cuban oregano. well with the average consumer’s gins, and the plant will grow to 3 (although few cooks use it twice…). Plectranthus argentatus is a strong, care or lack thereof. Consider feet in diameter in a season. It is a A close companion to Cuban upright, solid gray species. This is a working this plant into your strong performer in the southern Oregano is plectranthus forsteri horsy large plant with matt silver hanging basket and mixed con- landscape as well as in containers. foliage, similar to ‘Dusty tainer schedules; it is fast, has Unlike many of the other plectran- Miller’, though not as glossy green leaves, takes shade thus, which can be gangly without bright a gray. The plant and always looks good. This is a pinch, this plant has a good, lends itself to landscape definitely one to avoid full hot dense growth habit and looks use very nicely in much sun, as the leaves will scorch. good all the time. the same way as Dusty Plectranthus oertendahlii, The variety of textures, colors and Miller but with larger and Creeping Coleus, and plectran- forms available to growers make faster growing. In mixed thus fruticosus are two plectran- plectranthus a crop we should all containers, this plant will thus with purple-toned foliage. consider adding this spring. GPN take over if you don’t use In the industry, these two plants vigorous plants in the mix are often confused with one Richard Schoellhorn is associate pro- with it. another and sold synonymously. fessor of horticulture at the University For hanging basket However, P. oertendahlii is a of Florida, Gainesville, Fla. He can be culture, there are quite a smaller leaved plant with promi- reached by phone at (352) 392-1831 or few plectranthus to nent silver veins on a purple- by E-mail at rksch@ufl.edu. choose from and all of green leaf, and P. fruticosus has these work equally well larger leaves and a more general LearnMore! in mixed containers. purple tone overall. Both are For more information Most of these plants strong hanging basket plants related to this article, go to www.onhort.com/LM.CFM/gp flower sporadically in and add purple tones to mixed 020207 P. ecklonii late summer, but they containers.

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